First-principles calculation of defect energetics in cubic-BaTiO3 and a comparison with SrTiO3

Lee, Hak Sung; Mizoguchi, Teruyasu; Yamamoto, Takahisa; Kang, Suk Joong L.; Ikuhara, Yuichi

doi:10.1016/j.actamat.2007.07.054

Cited by 67 publications

(49 citation statements)

References 24 publications

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“…The detailed calculation method of point defect formation energy is well summarized in the literature 30 and applied for various oxide materials. [16][17][18] Figure 1 shows the schematic illustration of the Gd-Ti-O pseudo ternary phase diagram. Because the chemical potential µ i of element i (i = Gd, Ti, O) is dependent on the equilibrium condition, the following equilibrium conditions were considered at each equilibrium point shown in Fig.…”

Section: A First-principles Calculationmentioning

confidence: 99%

Theoretical and experimental investigation of defect formation / migration in Gd2Ti2O7: General rule of oxide-ion migration in A2B2O7 pyrochlore

et al. 2016

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We investigated the intrinsic defect formation energy and oxide-ion migration mechanism in Gd2Ti2O7 pyrochlore. It was found that the vacancy formation energy of Gd is lower than that of Ti. For the oxygen vacancy, O(48f) was found to show lower vacancy formation energy than O(8b). The formation energy of the vacancy complex showed that the Gd vacancy is accompanied with the O(48f) vacancy, which is consistent with our experiment. The migration energy of O(48f) along the <100> direction, which is dominant migration path for ionic conduction, was calculated to be 0.43 eV. On the other hand, we found that Gd vacancy increases O(48f) migration energy. For example, the migration energy of O(48f) along the <100> direction was increased to be 1.36 eV by the local compressive strain around Gd vacancy. This finding could explain our previous experimental result of decreasing conductivity with increasing Gd deficiency. Along with the oxide-ion migration mechanism in Gd2Ti2O7, O(48f) migration energies along both <100> and <110> directions for various A2B2O7 pyrochlore structures were investigated. As a general trend of oxide-ion migration in the pyrochlore structure, we propose that O(48f) migration along the <100> direction is governed by the strength of B–O bonding. On the other hand, the ratio of ionic radius B/A is proposed to determine O(48f) migration along the <110> direction in A2B2O7 pyrochlore.

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Section: A First-principles Calculationmentioning

confidence: 99%

Theoretical and experimental investigation of defect formation / migration in Gd2Ti2O7: General rule of oxide-ion migration in A2B2O7 pyrochlore

et al. 2016

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“…Figure 3 shows a schematic phase diagram of the ternary Ca-Ti-O system, and the vertices of three phase regions were named A$G as for the previous reports. 15,16) The values of the atomic chemical potential of three elements were evaluated at those points. Here, it was assumed that CaTiO 3 was stable at every point, so that the chemical potentials of the three elements were obtained from the combinations of the chemical potentials of Ca, CaO, Ti, TiO, 30) The heats of formation obtained from the calculations are summarized in Table 1.…”

Section: Defect Formation Energymentioning

confidence: 99%

“…Although the defect energetics of SrTiO 3 and BaTiO 3 has been studied so far, [13][14][15][16] there are only a few reports on the defect energetics in CaTiO 3 . Recently Mather et al reported the energetics of defects, dopant-vacancy association, and the nanoscale clusters formation in orthorhombic CaTiO 3 based on a static lattice calculation with empirical pair potentials.…”

Section: Introductionmentioning

confidence: 99%

First Principles Study on Intrinsic Vacancies in Cubic and Orthorhombic CaTiO<SUB>3</SUB>

et al. 2009

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The structural relaxations and the formation energies of intrinsic defects in cubic and orthorhombic CaTiO 3 were investigated by a first principles projector-augmented wave method. It was found that cations and oxygen vacancies in both phases cause extra levels near the valence band maximum and the conduction band minimum, respectively, and the Ti-vacancy induced level in orthorhombic CaTiO 3 is closer to the valence band maximum than that in cubic CaTiO 3 . Among the neutral defect species, including neutral isolated vacancy, partial Schottky, and full Schottky, it was found that the V Ca 2À þ V O 2þ and V O 0 are the most preferable defect species for orthorhombic CaTiO 3 under reduction and oxidization conditions, respectively, whereas the V Ca 2À þ V O 2þ partial Schottky is always stable in any atmosphere in cubic CaTiO 3 . As compared to cubic CaTiO 3 , it was found that orthorhombic CaTiO 3 shows higher defect formation energies.

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“…Similar to the previous study, the magnitude of the atomic relaxation was estimated from the distance between the vacancy site and the first nearest neighbor atoms. 10),21), 22) We averaged the value when there was more than one nearest neighbor bond. The magnitude of the atomic relaxation was calculated by following equation;…”

Section: Resultsmentioning

confidence: 99%

Defect formation energetics at the grain boundary in CuInSe<sub>2</sub> using first-principles calculations

Yamaguchi

Mizoguchi

2014

J. Ceram. Soc. Japan

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We investigated defect formation energetics at the grain boundary (GB) in CuInSe 2 (CIS) using first-principles calculations. We focused on the (112) ) were investigated in the bulk and GB. We found that CIS shows characteristic atomic relaxation after vacancy formation, and V Cu 0 is the most energetically favorable defect in both the bulk and the GB. Furthermore, we found that (112)[1 10] ∑3 twin GB does not promote the formation of the Cu vacancy under all conditions, whereas it relatively promotes the formation of the Se vacancy under metal-rich conditions.

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First-principles calculation of defect energetics in cubic-BaTiO3 and a comparison with SrTiO3

Cited by 67 publications

References 24 publications

Theoretical and experimental investigation of defect formation / migration in Gd2Ti2O7: General rule of oxide-ion migration in A2B2O7 pyrochlore

Theoretical and experimental investigation of defect formation / migration in Gd2Ti2O7: General rule of oxide-ion migration in A2B2O7 pyrochlore

First Principles Study on Intrinsic Vacancies in Cubic and Orthorhombic CaTiO<SUB>3</SUB>

Defect formation energetics at the grain boundary in CuInSe<sub>2</sub> using first-principles calculations

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